We report tests of local position invariance and the variation of fundamental constants from measurements of the frequency ratio of the 282-nm Hg+199 optical clock transition to the ground state hyperfine splitting in Cs133. Analysis of the frequency ratio of the two clocks, extending over 6 yr at NIST, is used to place a limit on its fractional variation of <5.8×10-6 per change in normalized solar gravitational potential. The same frequency ratio is also used to obtain 20-fold improvement over previous limits on the fractional variation of the fine structure constant of |α̇α|<1.3×10-16yr-1, assuming invariance of other fundamental constants. Comparisons of our results with those previously reported for the absolute optical frequency measurements in H and Yb+171 vs other Cs133 standards yield a coupled constraint of -1.5×10-15<α̇/ α<0.4×10-15yr-1 and -2.7×10-15<ddtln μCsμB<8.6×10-15yr-1.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy(all)